Synthetic sports surface

ABSTRACT

A pre-formed synthetic turf module ( 10 ) includes a base tray ( 12 ), a flexible backing sheet ( 36 ) tufted with synthetic ribbons simulating grass blades, and a granular media infill material ( 40 ) in the voids between the ribbons, the tufted backing sheet and infill material being supported on the base tray so that a plurality of the modules may be installed side-by-side to form a media-filled synthetic turf surface. Each module may also include a peripheral wall ( 14 ) which is removed during the installation. A method of installing a synthetic turf surface, and the installation of heating elements ( 50 ) in the surface, are also disclosed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a synthetic turf surface and a method ofinstallation. In particular, the invention relates to a synthetic sportsand recreation surface with improved ease of installation.

2. State of the Art

Synthetic turf is known and widely used for recreational areas and forsporting pursuits such as tennis, lawn bowls, horse racing, hockey andfootball. Such synthetic turf surfaces are formed as a flexible backingsheet into which is stitched (tufted) parallel rows of synthetic ribbonswhich extend upwards of the backing sheet to simulate blades of grass.The ribbon length and thickness, the gauge between the rows, and thetufting rate between adjacent tufts in each row, will depend on theintended use of the surface. A backing layer, such as latex, may beapplied to the back of the backing sheet.

A particulate material, such as one or more layers of sand or crumbedrubber, is used as an infill material between the ribbons, to hold theribbons generally upright and to provide resilience to the sportssurface. The infill level typically extends to a short distance belowthe tips of the ribbons, so that the exposed ribbon tips resemble theappearance and playing characteristics of grass.

The prior art synthetic turf surfaces are manufactured, transported andinstalled in large rolls, typically sheets about 50 m by 3.7 m,comprising the backing sheet, any backing layer and the tufted ribbons.The particle size, shape and resilience of the infill material isimportant to the playing characteristics of the resulting surface, andtherefore this infill material is typically sourced by tie syntheticturf manufacturer and transported with the rolls.

After preparation of the supporting surface, the synthetic turf rollsare rolled out with the ribbon side up. Joins between adjacent rolls areeffected by taping and/or stitching the unrolled sleets together. Oncethe synthetic turf is positioned and appropriately tensioned, the infillmaterial is distributed over the turf and groomed to the desired level.

This installation method is time-consuming. Where the installation istemporary, eg. for an indoor tennis tournament lasting about a week,installation and removal of the tennis surface may take almost as longas the tournament itself.

SUMMARY OF THE INVENTION

The present invention aims to provide a synthetic surface constructionwhich allows a more convenient installation method.

The present invention provides a pre-formed synthetic turf moduleincluding:

-   -   a base tray;    -   a flexible backing sheet tufted with a plurality of synthetic        ribbons extending upwards of the backing sheet to represent        grass blades; and    -   a granular media infill material on the backing sheet in the        voids between the ribbons;        said base tray supporting said tufted backing sheet and media        such that said modules are adapted to be installed side-by-side        with one or more similar modules so as to form a media-filled        synthetic turf surface.

Preferably, a peripheral wall is attached to said base tray forretaining said media on the module during transport and installation ofthe module. More preferably, the peripheral wall is removable afterinstallation.

Preferably also, the base tray is configured so as to allow drainage toa drainage space between the underside of the tray and a supportingsurface.

A further form of the invention provides a pre-formed synthetic turfmodule including:

-   -   a base tray;    -   a flexible backing sheet tufted with a plurality of synthetic        ribbons extending upwards of the backing sheet to represent        grass blades; and    -   a media infill material on the backing sheet in the voids        between the ribbons, said infill material including a lower        fused layer of infill material and an upper layer of granular        media infill material;        said base tray supporting said tufted backing sheet and media        such that said modules are adapted to be installed side-by-side        with one or more similar modules so as to form a media-filled        synthetic turf surface.

A further form of the invention provides a method of installing asynthetic turf surface comprising a plurality of modules.

Further preferred embodiments will now be described with reference tothe accompanying drawings:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective of the base plate and peripheral wallof the base tray;

FIG. 2 is a perspective of the base plate and wall of FIG. 1 whenassembled;

FIG. 3 is a detail of the corner portion of the FIG. 2 assembly;

FIGS. 4A and 4B show the catch arrangement attaching the wall to thebase plate;

FIG. 5 is a bottom perspective of the tray;

FIG. 6 is a schematic cross-sectional elevation of the adjoining regionof two adjacent modules;

FIG. 7 shows the arrangement of FIG. 6 after removal of the wall andgrooming of the surface;

FIG. 8 illustrates an alternative infill arrangement;

FIGS. 9 and 10 are schematic cross-sectional elevations showinginclusion of tubes for heating the sports surface;

FIG. 11 is a schematic plan showing the arrangement of the heatingtubes; and

FIGS. 12A and 12B are schematic cross-sectional elevations of analternative peripheral wall and peripheral flange arrangement takenthrough the catch and midway along a side of the module, respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1 and 2, the base tray 10 of each modulecomprises a base plate 12 with a removable peripheral wall 14.

The base plate 12 is sufficiently rigid to support the weight of thecompleted module during transport and installation, and preferablyformed of a non-biodegradable plastics material such as polypropylene orpolystyrene. The base plate may have stiffening ribs 16 in its us and/orlower surfaces (see FIG. 5) and one or more drainage formations tofacilitate drainage of water from the synthetic turf installation whenlaid.

The tray is preferably substantially square or rectangular in plan view,but may be any other shape which allows a substantially continuousplaying surface to be formed when a plurality of the modules are laidside by side. The tray is preferably of a size which allows thecompleted module to be lifted and handled by one person, for exampleabout 500 mm by 500 mm. The base plate has a 10-20 mm peripheral flange18 which allows for removable attachment of the peripheral wall 14, andmay have cut-off portions 20 at its corners to assist drainage (see FIG.3). A small flange 21, about 2-4 mm high, may be provided adjacent thecut-off portion, to retain the free-flowing glue used to adhere thesynthetic turf to the tray without significantly affecting drainage.

The peripheral wall 14 is preferably about 50-100 mm high, morepreferably about 60-70 mm, and of sufficient rigidity to retain thegranular media in the completed module. The wall may suitably be formedof extruded or moulded plastics material such as a polystyrene orpolypropylene. The lower portion of the wall has spaced recesses 22 forreceiving detents 24 on the flange 18, as will be described in furtherdetail later with reference to FIGS. 4A and 4B.

The peripheral wall is adapted to be collapsible for stacking afterremoval from the installed module, so that the wall may be returned tothe factory for re-use. To this end, the corners 26 of the walls 14 maybe hinged, so that the walls maybe collapsed to a relatively flattransport position.

The module may also be provided with a lid (not shown) for transport,which also may be returned to the factory for re-use.

With reference to FIGS. 4A and 4B, the peripheral flange 18 of the baseplate 12 has one or more resilient detents 24 which engage with therecesses 22 in the peripheral wall 14 to hold the wall in position. Thebase plate may also have a second peripheral flange—a small locatingflange 28 with a ramped end 30 which as in correct location of the wall,as best shown in FIG. 4B.

The attachment of the wall to the base plate is adapted to release uponapplication of sufficient upwards force to the wall, so that the wallsmay be removed from the modules after the installation.

FIGS. 12A and 12B show a cross-section of a modified construction of theperipheral flange and wall arrangement, in which the locating flange 28is taller then that in FIGS. 4A and 4B. Preferably, the locating flangevaries in height from approximately one half the height of the manperipheral flange 18 near the corners of the tray (FIG. 12A) toapproximately the full height of flange 18 at the centre of each side(FIG. 12B). The lower portion of the peripheral wall 14 is rebated tomatch the locating flange 28, so that the bottom edge of the wall isheld between the flanges 18 and 28. The outer surface of the wall 14 hase recesses 22 which engage with detents 24 on flange 18 (FIG. 12B).

The top edge of the peripheral wall 14 in FIGS. 12A and 12B has aninwardly turned lip 52, which assists with gripping of the wall by theinstaller during removal, and also helps retain infill on the moduleduring installation. Optionally, the top of the wall 14 may also have atab (not shown) protruding above the top of the artificial turf surfacewhen laid, as visible indication of those modules which have not yet hadtheir peripheral walls 14 removed.

In the embodiment of FIGS. 12A and 12B, the locating flange 28 continuesinto the corners of the tray, in place of small flange 21 in FIG. 3, toretain the glue, while peripheral flange 18 is discontinued at thecorners to facilitate drainage.

FIG. 5 shows the bottom of the base plate, with a pattern of ribs 16 andglue points 34 formed in the lower surface. The ribs add stiffness tothe tray for transport and handling of the module, and also serve tospace the lower surface of the tray from the supporting surface to forma drainage gap. Preferably, the rib pattern is adapted to assist lateraldrainage along this drainage gap, as is the rid pattern shown in FIG. 5.

FIG. 6 is a cross section elevation of two abutting modules beforeremoval of the peripheral walls. Each module consists of a square basetray of the type described above, with a section of media-filledsynthetic turf therein. The synthetic turf square is adhered to the topof the base plate, and sized to fit inside the peripheral wall.

The construction of synthetic turf is well known. Each synthetic turfsection comprises a flexible backing sheet 36 formed as one or morelayers, into which is tufted parallel rows of synthetic ribbons 38 whichsimulate grass. The type, thickness, pile length and pattern of theribbons, the gauge between adjacent rows and the stitch rate within eachrow can be varied to suit the particular use for the synthetic turf, asis known in the art.

The granular material infill 40 may be of any suitable type, such assand, ground rubber, plastic beads or combinations thereof, depending onthe end use for the synthetic turf surface. The media typically comes upto a level about 5 mm to 10 mm below the tips of the pile, so that thetips are exposed to simulate the look and playing characteristics ofgrass.

The module construction described above with reference to the Figures isadapted for use with pile lengths up to about 100 mm. Where it isdesired to use pile lengths in excess of this, a higher peripheral wallmay be desirable.

As shown in FIG. 6, the peripheral walls 14 retain the infill 40 duringtransport and initial installation of the modules. After positioning andfixing of the modules to the supporting surface 42, the peripheral wallsare removed and the surface groomed to level the infill to result in thearrangement shown in FIG. 7. If desired, some additional infill may beadded during this grooming process, but this will usually be relativelyminor compared to filling and grooming of conventional synthetic turf.

It will be apparent from FIGS. 6 and 7 that the thickness of theperipheral walls and the edge lips 44 of the base plates be kept assmall as practical, while still providing adequate strength anddrainage. Preferably, the total distance between the inside surfaces ofthe peripheral walls of abutting modules is less than about 15-20 mm,more preferably a 12 mm or less. In this way, the spacing between theedge rows of ribbons in abutting modules will not be noticeably largerthan the gauge of the pile, so the joins will not be visible in theplaying surface.

The illustrated embodiment thus allows rapid and convenient installationof a synthetic turf surface, even in weather conditions which mightimpede laying and filling of a conventional surface. Also, the modulesmay be repositioned after installation, so that worn sections from highwear areas can be replaced, or swapped with less worn ones.

By providing an arrangement in which the synthetic turf is adhered tothe base tray of the module and the infill material added in thefactory, the invention also allows the use of the novel and inventiveinfill arrangement shown in FIG. 8. In that arrangement, which isparticularly advantageous for long pile synthetic turfs over about 25mm, a base layer 46 of the infill is formed by adding an infill layer offoamed plastics beads and heating the turf and infill in the module sothat the beads fuse together. One or more additional infill layers 48may then be applied.

Desirably, this method may be carried out by applying an infill of 2-3mm beads of foamed polystyrene or other suitable plastics material, andapplying steam or other heat source to expand the beads to form alightly fused layer. Care must be taken not to subject the base tray andsynthetic turf to excessive temperatures during this operation. Thefused base layer may then be covered by sand, rubber or other knowninfill materials.

FIGS. 9 and 10 show the abutment of two adjacent modules, includingheating fluid tubes 50 laid in the spaces between the peripheral walls14 and/or peripheral flanges 18 of the modules prior to removal of thewalls 14 (FIG. 9). These heating fluid tubes 50 become covered with thegranular material 40 when the peripheral walls 14 are removed (FIG. 10).

The heating tubes 50 are preferably flexible, and of sufficiently smalldiameter (e.g 8-10 mm) to fit between the adjacent modules and lay deepenough within the infill material 40 to avoid damage during use of thesurface.

With reference to FIG. 11, the tubes 50 are connected to sources of hotwater or other fluid, to heat the sports surface sufficiently to keep itsubstantially clear of snow and ice.

Preferably, the tubes are laid parallel, along opposed edges of eachmodule, with the hot fluid direction alternating between rows,transversely across the field as shown schematically in FIG. 11.However, where the synthetic sports surface is laid in an area ofextreme cold or heavy snowfall, it will be possible to lay the heatingtubes 50 in both the transverse and longitudinal directions, with thetubes 50 being protected by the particulate material 40 even in theregions of overlap.

In an unillustrated embodiment, the heating tubes may be replaced by lowvoltage heating elements for heating the sports surface.

While the invention has been described above with reference to syntheticturfs which simulate the appearance of grass, it should be appreciatedthat the invention also may be used for synthetic ‘turf’ of the typewhich simulates a clay surface, in which the infill level extends abovethe tips of the pile.

While particular embodiments of this invention have been described, itwill be evident to those skilled in the art that the present inventionmaybe embodied in other specific forms without departing from theessential characteristics thereof. The present embodiments and examplesare therefore to be considered in all respects as illustrative and notrestrictive, and all modifications which would be obvious to thoseskilled in the art are therefore intended to be embraced therein. Itwill further be understood that any reference herein to known prior artdoes not, unless the contrary indication appears, constitute anadmission that such prior art is commonly known by those skilled in theart to which the invention relates.

1. A pre-formed synthetic turf module including: a base tray including aperipheral wall that defines enclosed space accessible from above saidbase tray, said enclosed space for retaining a flexible backing sheetand granular infill material therein; an outwardly protruding lipextending away from a lower portion of said peripheral wall; saidflexible backing sheet tufted with a plurality of synthetic ribbonsextending upwards of the backing sheet to represent grass blades; andsaid granular media infill material disposed on the backing sheet in thevoids between the ribbons; said base tray supporting said tufted backingsheet and said granular infill material such that said module is adaptedto be installed side-by-side with one or more similar modules so as toform a media-filled synthetic turf surface, said lip defining a spacethereabove for retaining granular media infill material between theperipheral walls of two adjacent modules when said two adjacent modulesare installed side-by-side.
 2. A pre-formed synthetic turf moduleaccording to claim 1 wherein said peripheral wall is attached to saidbase tray for retaining said media on the module.
 3. A pre-formedsynthetic turf module according to claim 2 wherein said peripheral wallis removable from said base tray after installation of the module.
 4. Apre-formed synthetic turf module according to claim 3 wherein saidperipheral wall is collapsible after removal from said base tray.
 5. Apre-formed synthetic turf module according to claim 4 wherein saidperipheral wall includes one or more hinge portions configured to allowcollapsing of said peripheral wall.
 6. A pre-formed synthetic turfmodule according to claim 3 wherein the base tray includes a peripheralflange which retains said peripheral wall.
 7. A pre-formed syntheticturf module according to claim 6 wherein the peripheral flange andperipheral wall have co-operating engagement means for retaining theperipheral wall.
 8. A pre-formed synthetic turf module according toclaim 7 wherein said engagement means includes a detent in saidperipheral flange which engages with a recess in said peripheral wall.9. A pre-formed synthetic turf module according to claim 6 wherein saidperipheral flange is discontinuous at one or more corners of said basetray.
 10. A pre-formed synthetic turf module according to claim 9wherein said backing sheet is glued to said base tray using a glue, andsaid base tray includes a further peripheral flange which is continuous,said continuous peripheral flange being adapted to prevent said gluefrom escaping through said discontinuous flange on said base tray.
 11. Apre-formed synthetic turf module according to claim 1 wherein said basetray includes one or more projections on an underside thereof, so as toform a drainage space between said base tray and a supporting surface.12. A pre-formed synthetic turf module according to claim 1 wherein saidspace is adapted to accommodate at least one heating element betweensaid adjacent modules.
 13. A pre-formed synthetic turf module accordingto claim 12 wherein said heating element is selected from the groupincluding an electric heating element and a heating fluid tube.
 14. Apre-formed synthetic turf module including: a base tray including aperipheral wall that defines enclosed space accessible from above saidbase tray, said enclosed space for retaining a flexible backing sheetand media infill material therein; an outwardly protruding lip extendingaway from a lower portion of said peripheral wall; said flexible backingsheet tufted with a plurality of synthetic ribbons extending upwards ofthe backing sheet to represent grass blades; and said media infillmaterial disposed on the backing sheet in the voids between the ribbons,said media infill material including a lower fused layer of infillmaterial and an upper layer of granular infill material; said base traysupporting said tufted backing sheet and media infill material such thatsaid module is adapted to be installed side-by-side with one or moresimilar modules so as to form a media-filled synthetic turf surface,said lip defining a space thereabove for retaining media infill materialbetween the peripheral walls of two adjacent modules when said twoadjacent modules are installed side-by-side.
 15. A pre-formed syntheticturf module according to claim 14 wherein said fused layer is formedfrom fused beads of foamed plastics material.
 16. A pre-formed syntheticturf module according to claim 15 wherein said beads are fused by steamapplied to said module before application of said upper layer.
 17. Apre-formed synthetic turf module according to claim 14 wherein saidspace is adapted to accommodate at least one heating element betweensaid adjacent modules.
 18. A pre-formed synthetic turf module accordingto claim 17 wherein said heating element is selected from the groupincluding an electric heating element and a heating fluid tube.